title: miR-29b induces SOCS-1 expression by promoter demethylation and negatively regulates migration of multiple myeloma and endothelial cells.
abstract: Epigenetic silencing of tumor suppressor genes frequently occurs and may account for their inactivation in cancer cells. We previously demonstrated that miR-29b is a tumor suppressor microRNA (miRNA) that targets de novo DNA methyltransferases and reduces the global DNA methylation of multiple myeloma (MM) cells. Here, we provide evidence that epigenetic activity of miR-29b leads to promoter demethylation of suppressor of cytokine signaling-1 (SOCS-1), a hypermethylated tumor suppressor gene. Enforced expression of synthetic miR-29b mimics in MM cell lines resulted in SOCS-1 gene promoter demethylation, as assessed by Sequenom MassARRAY EpiTYPER analysis, and SOCS-1 protein upregulation. miR-29b-induced SOCS-1 demethylation was associated with reduced STAT3 phosphorylation and impaired NFκB activity. Downregulation of VEGF-A and IL-8 mRNAs could be detected in MM cells transfected with miR-29b mimics as well as in endothelial (HUVEC) or stromal (HS-5) cells treated with conditioned medium from miR-29b-transfected MM cells. Notably, enforced expression of miR-29b mimics increased adhesion of MM cells to HS-5 and reduced migration of both MM and HUVEC cells. These findings suggest that miR-29b is a negative regulator of either MM or endothelial cell migration. Finally, the proteasome inhibitor bortezomib, which induces the expression of miR-29b, decreased global DNA methylation by a miR-29b-dependent mechanism and induced SOCS-1 promoter demethylation and protein upregulation. In conclusion, our data indicate that miR-29b is endowed with epigenetic activity and mediates previously unknown functions of bortezomib in MM cells.
authors.affiliation: Department of Experimental and Clinical Medicine; Magna Graecia University and Medical Oncology Unit; T. Campanella Cancer Center; Salvatore Venuta University Campus; Catanzaro, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Amodio
authors.forename: Dina
authors.initials: D
authors.lastname: Bellizzi
authors.forename: Marzia
authors.initials: M
authors.lastname: Leotta
authors.forename: Lavinia
authors.initials: L
authors.lastname: Raimondi
authors.forename: Lavinia
authors.initials: L
authors.lastname: Biamonte
authors.forename: Patrizia
authors.initials: P
authors.lastname: D'Aquila
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Di Martino
authors.forename: Teresa
authors.initials: T
authors.lastname: Calimeri
authors.forename: Marco
authors.initials: M
authors.lastname: Rossi
authors.forename: Marta
authors.initials: M
authors.lastname: Lionetti
authors.forename: Emanuela
authors.initials: E
authors.lastname: Leone
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Passarino
authors.forename: Antonino
authors.initials: A
authors.lastname: Neri
authors.forename: Antonio
authors.initials: A
authors.lastname: Giordano
authors.forename: Pierosandro
authors.initials: P
authors.lastname: Tagliaferri
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Tassone
mesh_terms: D002465:Cell Movement / Q000235:genetics; D019175:DNA Methylation; D005786:Gene Expression Regulation; D015972:Gene Expression Regulation, Neoplastic; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000235:genetics* / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: D016209:Interleukin-8; C532045:MIRN29a microRNA, human; D035683:MicroRNAs; D016328:NF-kappa B; C108944:SOCS1 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D042461:Vascular Endothelial Growth Factor A
keywords: epi-miRNA; methylation; miR-29b; microRNA; multiple myeloma